/* Header */
.header {
    background-color: #fff;
    border-bottom: 1px solid #e2e8f0;
    position: sticky;
    top: 0;
    z-index: 100;
}

.navbar {
    padding: 1rem 0;
}

/* 移动端导航栏优化 */
@media (max-width: 768px) {
    .navbar {
        padding: 0.75rem 0;
    }
}

@media (max-width: 480px) {
    .navbar {
        padding: 0.5rem 0;
    }
}

.navbar .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav-brand .brand-link {
    display: flex;
    align-items: center;
    font-size: 1.5rem;
    font-weight: 700;
    color: #2d3748;
    text-decoration: none;
}

.nav-brand .brand-link i {
    color: #3182ce;
    margin-right: 0.5rem;
}

.nav-menu {
    display: flex;
    align-items: center;
}

.nav-list {
    display: flex;
    list-style: none;
    margin: 0;
}

.nav-item {
    margin: 0 1rem;
}

.nav-link {
    color: #4a5568;
    font-weight: 500;
    text-decoration: none;
    padding: 0.5rem 0;
    transition: color 0.2s;
}

.nav-link:hover,
.nav-link.active {
    color: #3182ce;
}

.nav-search {
    margin-left: 2rem;
}

.search-form {
    display: flex;
    align-items: center;
    background-color: #f7fafc;
    border-radius: 6px;
    padding: 0.5rem;
}

.search-input {
    border: none;
    background: none;
    padding: 0.5rem;
    font-size: 14px;
    width: 200px;
    outline: none;
}

.search-btn {
    background: none;
    border: none;
    color: #4a5568;
    cursor: pointer;
    padding: 0.5rem;
}

.nav-toggle {
    display: none;
    flex-direction: column;
    cursor: pointer;
}

.nav-toggle .bar {
    width: 25px;
    height: 3px;
    background-color: #4a5568;
    margin: 3px 0;
    transition: 0.3s;
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-menu {
        display: none;
    }
    
    .nav-toggle {
        display: flex;
    }
    
    .search-input {
        width: 120px;
    }
    
    /* 移动端导航栏优化 */
    .navbar .container {
        padding: 0 12px;
    }
    
    .nav-brand .brand-link {
        font-size: 1.3rem;
    }
    
    .nav-search {
        margin-left: 1rem;
    }
}

@media (max-width: 480px) {
    .search-input {
        width: 100px;
        font-size: 13px;
    }
    
    .navbar .container {
        padding: 0 8px;
    }
    
    .nav-brand .brand-link {
        font-size: 1.2rem;
    }
    
    .nav-brand .brand-link span {
        display: none;
    }
    
    .nav-brand .brand-link::after {
        content: "PTR";
        font-weight: 700;
    }
}

@media (max-width: 360px) {
    .navbar .container {
        padding: 0 5px;
    }
    
    .nav-brand .brand-link {
        font-size: 1.2rem;
    }
    
    .btn {
        padding: 10px 16px;
        font-size: 14px;
    }
}